Solar Trough Mirror Shape Specifications

Abstract

The performance of concentrating solar collectors depends to a significant amount on the shape accuracy of the mirrors reflecting the sunlight onto the absorber. For the case of parabolic trough mirrors and on the basis of previous work on shape measurements and ray-tracing, a quality parameter has been defined, that quantifies the average deviation of the reflected beam from the design focal line. It could be demonstrated that application of standard distribution (Gauss distribution) is sufficiently related to derive the performance relevant intercept factor from it. As objective for the glass reflector for high performance trough collectors a typical value for the focus deviation RMS in transversal direction is about 15% of the absorber diameter.